Aluminum alloy miniature cartridge fuses

Abstract

A high-capacity miniature cartridge fuse is provided. A fuse includes a cylindrical housing, a fusible wire, and first and second deep-drawn ferrules fabricated from aluminum alloy. The aluminum is plated with nickel. The ferrule includes a side wall and an end wall. The side wall surrounds the first or second end of the housing, and has a thickness of approximately 0.50 mm or less. The end wall includes a boss extending toward an interior of the housing, and has a thickness greater than the thickness of the side wall.

What is claimed is: 
     
       1. A high-capacity miniature cartridge fuse comprising:
 a cylindrical housing having opposing first and second ends; 
 a fusible element positioned inside the cylindrical housing and including opposing first and second ends; and 
 first and second deep-drawn ferrules fabricated from aluminum alloy, the aluminum alloy ferrules fabricated to withstand high pressure generated inside the cylindrical housing as a result of arcing and to stay in place after repeated temperature and pressure changes caused by at least one of i) current or ii) arcing during short circuit events, wherein the first and second ferrules are respectively attached to the first and second ends of the cylindrical housing and electrically connected to the respective first and second ends of the fusible element, the aluminum alloy being plated with nickel, each of the first and second ferrules comprising:
 a side wall surrounding the first or second end of the cylindrical housing, wherein the side wall has a thickness of approximately 0.50 mm or less; and 
 an end wall extending from the side wall and closing the first or second end of the cylindrical housing, wherein the end wall includes a boss extending toward an interior of the cylindrical housing and defining an interior surface of the end wall, and the end wall has a thickness greater than a thickness of the side wall, 
 
 wherein the side wall and the end wall define an interior receptacle that is sized to receive the first or second end of the cylindrical housing, 
 wherein the fuse is configured as a time delay fuse, and the aluminum alloy has a thermal conductivity of approximately 125 W/m·K or lower and an electrical resistivity of approximately 5.32×10 −6  Ω-cm or higher. 
 
     
     
       2. The fuse of  claim 1 , wherein the fuse has a maximum breaking capacity of 6000 Amperes. 
     
     
       3. The fuse of  claim 1 , wherein the aluminum alloy has a tensile strength of approximately 138 MPa or higher. 
     
     
       4. The fuse of  claim 1 , wherein the aluminum alloy has a yield strength of approximately 117 MPa or higher. 
     
     
       5. The fuse of  claim 1 , wherein the aluminum alloy has a melting point of approximately 590° C. or higher. 
     
     
       6. The fuse of  claim 1 , wherein a friction force between the side wall of the first or second ferrule and the cylindrical housing is approximately 150 Newton or higher. 
     
     
       7. The fuse of  claim 6 , wherein an inner diameter of the interior receptacle is greater than an outer diameter of the cylindrical housing by approximately 20 μm or less. 
     
     
       8. The fuse of  claim 1 , wherein the fusible element comprises two or more fusible wires. 
     
     
       9. The fuse of  claim 1 , further comprising an eyelet extending adjacent the interior surface of the end wall of the first or second ferrule, wherein the fusible element comprises a fusible wire, and the fusible wire extends through the eyelet and is held between a portion of the eyelet and the end wall of the first or second ferrule. 
     
     
       10. A method of fabricating a high capacity miniature cartridge fuse, the method comprising:
 providing a cylindrical housing, wherein the cylindrical housing comprises opposing first and second ends; 
 providing a sheet of aluminum alloy; 
 constructing a ferrule from the sheet of aluminum alloy by a drawn process, wherein the ferrule comprises a side wall and an end wall extending from the side wall, the side wall and the end wall define an interior receptacle that is sized to receive the first or second end of the cylindrical housing, the side wall has a thickness of approximately 0.50 mm or less, the end wall comprises a boss extending from the end wall in the same direction as the side wall and defining an interior surface of the end wall, and the end wall has a thickness greater than a thickness of the side wall, the aluminum alloy ferrule fabricated to withstand high pressure generated inside the cylindrical housing and stay in place after repeated temperature and pressure changes caused by at least one of i) current or ii) arcing during short circuit events; 
 plating the ferrule with nickel; 
 inserting a fusible wire inside the cylindrical housing, wherein the fusible wire comprises opposing first and second ends; 
 inserting the first or second end of the fusible wire through an eyelet; 
 turning the first or second end of the fusible wire away from a body of the fusible wire; 
 inserting the first or second end of the cylindrical housing of the fuse into the interior receptacle of the ferrule such that the first or second end of the fusible wire is held between a portion of the eyelet and the end wall of the ferrule; and 
 securing the ferrule onto the cylindrical housing by clamping the ferrule around the first or second end of the cylindrical housing, 
 wherein the fuse is configured as a time delay fuse, and the aluminum alloy has a thermal conductivity of approximately 125 W/m·K or lower and an electrical resistivity of approximately 5.32×10 −6  Ω-cm or higher. 
 
     
     
       11. The method of  claim 10 , wherein the fuse has a maximum breaking capacity of 6000 Amperes. 
     
     
       12. The method of  claim 10 , wherein the aluminum alloy has a tensile strength of approximately 138 MPa or higher. 
     
     
       13. The method of  claim 10 , wherein the aluminum alloy has a yield strength of approximately 117 MPa or higher. 
     
     
       14. The method of  claim 10 , wherein the aluminum alloy has a melting point of approximately 590° C. or higher. 
     
     
       15. The method of  claim 10 , wherein a friction force between the side wall of the ferrule and the cylindrical housing is approximately 150 Newton or higher. 
     
     
       16. The method of  claim 15 , wherein an inner diameter of the interior receptacle is greater than an outer diameter of the cylindrical housing by approximately 20 μm or less. 
     
     
       17. The method of  claim 10 , wherein providing a sheet of aluminum alloy further comprises applying a first heat treatment to the sheet of aluminum alloy. 
     
     
       18. The method of  claim 10 , further comprising applying a second heat treatment to the ferrule.